The SMDN0155 disc neodymium magnet is made from high-performance N52 NdFeB, with black Nickel coating. The dimension of this item is 3/4″ dia. × 3/8″ thick, magnetized through thickness, with the tolerance of ±0.004″ × ±0.004″. The weight of this super strong neodymium magnet is 0.044875 lbs. It can pull up to 29.71 lbs steel. And the surface field is up to 5233 gausses.